chapter 1 biology form 4

7/29/2019 chapter 1 biology form 4

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CELL STRUCTURE & CELL

ORGANISATION


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Organelles (little organ) tiny structures

inside a cell that perform specific functions for

a cell. Example: mitochondria, lysosome and

chloroplast.


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THE UNIQUENESS OF THE CELL

A cell is unique:

Specialisation Division of labour

Coordination and integration


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Living components of cell is called as

PROTOPLASM (cytoplasm + nucleus)

The cytoplasms contains ORGANELLES

- Perform specific functions which enable the

cell to function as a unit of life


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1. Mitochondrion (pl: Mitochondria): AC and PC

spherical / rod-shaped organelles

two membranes: Inner membrane form cristae

& Outer membrane regular and smooth

an energy source

site of cellular aerobic respiration

produces ATP (adenosine triphosphate)


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NUCLEUS

contains the genetic material

regulates and controls the activities of the cell

an organelle bounded by double (2)

layers of nuclear membrane with poresand selectivelypermeable

responsible forall cellular structure, chemical functions, growth and reproduction

separates the genetic materials (chromatin)from cytoplasm


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NUCLEOLUS

spherical structure within the nucleus

consists of DNA (deoxyribonucleic acid)

and RNA (ribonucleic acid) and proteins

visible when the cell is not dividing

synthesis RNA which is needed to

make ribosomes


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NUCLEOPLASM

fluid contained within the nucleus

highly viscous solid

made up of the chromatin and the nucleolus


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CHROMOSOMES

thread-like structures (consists of genetic

material)

appears as chromatin spread throughout the

nucleus in the form of tiny granules

chromatin condenses into chromosomes

(during cell division)

carry genetic information in its DNA


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ENDOPLASMIC RETICULUM(ER)

connected to the nuclear membrane

synthesises proteins, steroids and lipids

collects, stores and distributes protein, steroids andlipids

exists as rough ER and smooth ER

Rough ER: covered with ribosomes, flat sealed sacwhich continued from the nuclear membrane,transports protein, and have a large surface area for

chemical reactions. Smooth ER: does not have ribosomes, transports lipids

and presents in large amounts of cells.


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PLASMA MEMBRANE

cell membrane

thin membrane surround the cytoplasm of a

cell

selectively permeable / semi permeable

a protective and selective outer barrier

consistsof phospholipids and protein molecules


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GOLGI APPARATUS

bound sacs

processes, packages and transport moleculessynthesised in the cell

forms lysosomes

transports and stores lipids

synthesis of carbohydrate from hormone

changes protein into glycoprotein

excretes waste products out of the cell


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CYTOPLASM

aqueous solution (except nucleus)

stores water, enzymes, nutrient, salts and

dissolved gases

provided support, shape and protects the cell

organelles

medium for metabolic reactions

provides substances


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LYSOSOME (ac)

sac-like organelle with one membrane

digest proteins, lipids and carbohydrates

removes undigested materials releases enzymes to digest external materials


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CENTRIOLE (ac)

are paired cylindrical organelles

nine tubes with three tubules each

produces spindle during cell division (mitosisand meiosis)

migrate to the opposite poles of the cell

(during cell division will be discussed in

Chapter 5 Cell Division)


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CELL WALL (ac)

rigid and tough cellulose layer surrounding the

plasma membrane (cell membrane)

protects and supports the cell

maintains the shape

prevents the cell from busting (excessive

intake of water)

allows substances to move freely through the

cell wall


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CHLOROPLAST (pc)

disc / lens-shaped organelle

have two membranes: inner and outer

membrane

contains chlorophyll in the grana to trap

sunlight energy

carry out photosynthesis in the chlorophyll

storage of food and pigments


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CELL ORGANISATION

Unicellular

A single cell performs all thebasic life process. Example:Amoebasp.,Paramecium sp., Chlamydomonas, Bacteria

and Euglena. MulticellularAn organism consists of more

than one cell. Each group of cell specialized tocarry our life processes. Example: Homosapien (human), animals and plants. It has fivelevels of organisation


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Cells: basic units of structure and function.Example: Red blood cells and xylem vessel cells.

Tissues: made up of cells with similar in structure andfunction.Example: Epithelial tissues and vascular tissues.

Organs: made up of tissues that perform a specificfunction.

Example: Heart and flower. System: two of more organs that perform a specific

function.Example: Digestive system and root system.

Organisms: whole living thing that carry out all thebasic life processes.Example: Human and durian tree.


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CELL ORGANISATION in Amoeba sp.

Cell structure

Amoeba sp.: plasma membrane, food vacuole,

contractile vacuole, pseudopodium, nucleus,

ectoplasma, endoplasm.

Locomotion

Amoeba sp.: Pseudopodium (false foot) helps

it to move forward slowly and it is known

asamoeboid movement.


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Feeding

Amoeba sp.: Omnivore. Eat bacteria, plantcells, algae and other microscopic organisms.

Entrapment extend pseudopodium.

Engulfment

engulf tiny food (phagocytosis)with its pseudopodia.

Digestion food enclosed in food vacuole

Absorption

enzyme digests the bacteria

Egesting expel indigestible material.


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Reproduction

Amoeba sp.: two types of reproduction. Binary Fission nucleus divides (favourable

condition) and then follows by division of

cytoplasm. Two daughter cells are formed

(mitotic division).

Spore Formation spores form (bad

condition) and germinate into new amoeba

under favourable condition.


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Osmoregulation

Amoeba sp.: water moves into the cell by

osmosis and prevention of bursting, it has a

contractile vacuole.

Respiration

exchange gases throughout the whole cell

membrane


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Excretion

waste products are ammonia and carbon

dioxide by diffusion. Solid waste in

paramecium is expelled through its anal pore.


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CELL SPECIALISATION IN

MULTICELLULAR ORGANISMS


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MULTICELLULAR ORGANISMS consists of

more than one cell


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Zygote divides to form 2 identical daughter

cells and these cells in turn divide to form 4

identical cells which dividing repeatedly to

form an embryo


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These cells grow, change shape & adapt

themselves to carry out specific functions

They differentiate & become more specialised

in order to perform specific tasks more

efficiently


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CELL

TISSUES

ORGAN

SYSTEM

ORGANISM

h f ll l


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The necessity for cell specialisation

and cell organisation

Cell specialisation a process of change &

adaptation that a cell undergoes to give itspecial structures & specific functions.

Cell organisation important to multicellular

organisms as complex orgnisms requirevarious types of tissues, organs and systems to

function


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Specialisation is essential because..

Able to carry out a specific function more

efficiently

Division of works enables the organisms to

carry out various tasks and function in an

orderly manner

All living process can be carried out more

efficiently & enables them to achieve a highergrowth rate

CELL ORGANISATION IN HUMAN &


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CELL ORGANISATION IN HUMAN &

ANIMALS


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EPITHELIAL TISSUE

- Consists of 1 or more layers of cells

- Are tightly interconnected, little space between

- Form a continuous layer over body surfaces & inner lining of cavities

- Some also form glands

- Function: protection, secretion, absorption


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MUSCLE TISSUES

- Most abundant

- Composed of long cells called muscl fibres


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CONNECTIVE TISSUES- Consists of various types of cells and fibres separated by an

extracellular matrix

- Widely distributed and have many functions

- Underlies epithelial tissues consists of collagen, capillaries & spaces

- Eg: tendon, ligament, cartilage, bones, blood lymph & adipose tissue


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Connective

tissues

Functions

CARTILAGE - Packed collagen fibres form tendons & ligaments

- Cartilage is a strong yet flexible CT to provide support to

the nose, ears & cover the ends of bones at joints

- Also forms discs between vertebrae (cushion to absorb

pressure)

BONE TISSUE - Provide protection to organs in the body & support the

body

BLOOD - Regulating , transporting and protecting

LYMPH - The fluid which leaks out of blood capillaries

FAT CELLS - Stores energy & insulate the body


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NERVE TISSUES

- Composed of neurons

- Each neuron consists of a cell body & nerve fibres called dendrites &

axons

- Neurons -Specialised to transmit nerve impulses

- Nerve tissues control & coordinate activities of the body


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EFFERENT

NEURON INTERNEURONAFFERENT

NEURON


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AFFERENT (bipolar)

INTERNEURON

EFFERENT (multipolar)


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ORGANS

Formed by 2 or more types of tissues working

together to perform particular functions

Examples: heart, lungs, skin, kidneys, eyes and

ears

Example : HEART consists of cardiac muscle,

connective tissue, nerve tissue and epithelial

tissue -> work together to pump the blood


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SYSTEMS

Consists of several organs that cooperate to

carry out a living process such as the digestion

of food

11 major systems in human

An organ may belong to more than one

system.


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CELL ORGANISATION IN PLANTS

Plant cells also undergo cell specialisation.

Plants organs (leaves, stem, root) are formed

from 2 main types of tissues

Meristematic tissue

Permanent tissue


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Plant tissues

Meristematic tissues Permanent tissues

Apicalmeristem

Lateralmeristem

Epidermaltissue

Vasculartissue

xylem phloem

Ground tissue

Parenchyma Collenchyma Sclerenchyma


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MERISTEMATIC TISSUES

Consists of small cells, thin walls, large nuclei,

dense cytoplasm and no vacuoles

Young & actively dividing cells which have not

undergone differentiation


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Two types:

APICAL MERISTEMS Located at the tips of roots and buds of shoots

Undergo mitotic division to increase the number of

cells

LATERAL MERISTEMS

In the peripheral area of stems & roots

Responsible for secondary growth which add girth to

the plants


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PERMANENT TISSUES

Consist of more mature cells that are either

undergoing differentiation or already

undergone differentiation

3 types:

Epidermal

Ground

Vascular


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chapter 1 biology form 4

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